1. Field of the Invention
The present invention relates to a flat display technology and more particularly, to a liquid crystal display (LCD) and a backlight module driving device and method thereof.
2. Description of Related Art
In recent years, with great advancement in the fabricating technology of electrical-optical and semiconductor devices comes prosperous development in flat panel displays. Due to the advantageous features of LCDs such as high space utilization efficiency, low power consumption, free radiation, and low electrical field interference, LCDs have become the main stream on the market. An LCD generally includes an LCD panel and a backlight module. The LCD panel does not have a self-illuminating property. Therefore, the backlight module is disposed under the LCD panel so as to provide a surface light source required by the LCD panel to display images.
In the conventional technology, in order to increase color saturation of an LCD, those skilled in the art seek advancement in the LCD driving circuit and method. In addition, those skilled in the art use a backlight module with light emitting diode (LED) that has higher color purity to replace a backlight module that emits white light in the conventional technology. Although such method may effectively increase color saturation of an LCD, it also brings about many disadvantages. The following illustration explains the disadvantages of a conventional LED backlight module in connection with relevant drawings.
FIG. 1 illustrates a state diagram of a certain area pixel Pix_n of a conventional LCD panel and a timing diagram of a control signal BL_CS of an LED backlight module. It is obvious that from FIG. 1, the control signal BL_CS of the LED backlight module is constantly under operation mode so when the area pixel Pix_n of the LCD panel in a frame period FR (i.e. a time of a vertical synchronous signal V_SYNC) is under a transition state (i.e. a slash interlace area), the LED backlight module still continues to provide a surface light source to the LCD panel. That is, the control signal of the LCD panel is not related to the control signal of the LED backlight module, which results in motion blur of display images presented by the LCD.
Furthermore, the control signal BL_CS of the LED backlight module is generally a 600 Hz PWM signal. Thus, the transition frequency of the control signal BL_CS of the LED backlight module is higher than the frame rate of the LCD (generally 60 Hz). As a result, the electromagnetic interference (EMI) caused by the control signal BL_CS of the LED backlight module is too high and the overall EMI index of the LCD is greatly increased.